Environmentally stable, photochromic and thermotropic organohydrogels for low cost on-demand optical devices

Abstract Hypothesis The color-changing ability of creatures widely existed in nature has inspired the development of adaptive allochroic materials, which can respond to various external stimuli. Integrating multi-stimuli responsiveness and long-term stability in allochroic system are urgent for practical applications under complex circumstances. Experiments The photochromic/thermotropic organohydrogels (PTOs) comprised polyacrylamide and cationic cellulose (JR400) were prepared by facile free-radical polymerization and glycerol displacement. The coexisting covalent bonds and noncovalent interactions collaboratively reinforce the networks, endowing the PTOs with boosted stretchability and toughness. Findings The photochromic ammonium molybdate (Mo7) and thermo-sensitive poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (EPE) were made into networks. In these cooperative networks, each constituent performed their own function without disruption, including fast photochromism (10 s) and durable thermo-responsiveness. Importantly, the glycerol-water solvent bestowed the distinct anti-freezing (-30 °C) and anti-dehydration performances on the PTOs. Accordingly, the materials could serve as promising rewritable devices for high-resolution and long-term data storage/encryption. Moreover, on-demand PTO windows integrating UV-prevention and solar energy regulation with Tlum (92.96%) and ΔTsol (46.02%) could create comfortable and healthy environments for occupants. This work offers a new design strategy for low-cost, environmentally stable smart optical devices.